臺灣地區飲用水中消毒副產物流佈評估及受污染原水新興消毒副產物生成潛勢之探討

Occurrence of Disinfection By-Products (DBPs) in Finished Water and Formation of Emerging DBPs from Polluted Source Water in Taiwan

張慧嫺(Hui-Hsien Chang)

指導教授 ： 王根樹

國立臺灣大學/公共衛生學院/環境衛生研究所/博士(2011年)

https://doi.org/10.6342/NTU.2011.00647

摘要

飲用水水源中的有機物質，在飲用水處理流程中皆可能與消毒劑反應，產生具有不良健康效應的消毒副產物（Disinfection by-products，DBPs)。其中主要生成各種碳系消毒副產物（Carbonated DBPs，C-DBPs），主要包括三鹵甲烷（Trihalomethanes，THMs）及含鹵乙酸（Haloacetic acids，HAAs)。過去THMs與其健康效應相關的研究與議題，持續受到廣泛地討論。而HAAs因分析方法仍存在一些困難，且臺灣地區亦尚未訂定管制標準，故仍缺乏大規模之飲用水中含鹵乙酸濃度流佈資料。除一般TTHM與HAAs外，由於亞硝胺類化合物具有遠高於傳統C-DBPs之毒性或致癌性，且主要生成於使用氯胺消毒劑之淨水流程中，因此近年來專家學者將亞硝胺類化合物視為重要之新興含氮消毒副產物（Nitrogenated DBPs，N-DBPs），其中又以N-nitroso-dimethylamine（NDMA）為飲用水中最主要之生成物種。對於亞硝胺類化合物來說，除了氯胺消毒劑之外，水中溶解性有機氮（Dissolved organic nitrogen，DON）也經研究證實為重要的前驅物質；然而目前針對水中DON之種類、濃度及其與NDMA生成特性之相關研究仍相當缺乏，因此DON、氯胺與亞硝胺類化合物生成之機制與關係仍尚待釐清。
因此，本研究主要包含三個研究主題及工作內容：（1）於民國96年至98年間，共採集臺灣地區141座主要淨水場之原水、清水及配水樣本，進行一般水質參數、THMs及HAAs的樣品分析，以建立臺灣地區飲用水中含鹵乙酸之背景資料庫。（2）共選擇具有不同物化特性、結構及相對應於DON不同的組成特性之9種代表性含氮有機物質，分別與氯、氯胺及二氧化氯進行反應，以觀察DBPs生成之特性（包括nitrosamines、THMs及HAAs）。（3）收集並分析內湖汙水廠放流水及金門太湖淨水場原水之季節性水樣中DON濃度及組成特性，並利用DAX-8、XAD-4和MSC-1H三種樹脂，將水中DON分離後所得到不同組成物與不同消毒劑反應，以探討DBPs生成之趨勢。
本研究第一階段的調查結果顯示，臺灣地區飲用水中9種含鹵乙酸總濃度（HAA9）分佈在0.5至84.4 μg/L之間，而總三鹵甲烷濃度分佈在ND至133.2 μg/L之間，除了部分外島地區及南部地區飲用水中可能生成較高之DBPs濃度外，大多數飲用水樣品中C-DBPs濃度皆可符合現階段臺灣地區或是美國施行的管制標準。而由於各地地區原水水質有所差異，因此C-DBPs之檢測結果也顯示夏季生成濃度較高之季節性變化，及外島地區水中含有較高C-DBPs濃度的區域性變化趨勢，同時在外島地區的飲用水中亦可觀察到較高含量的含溴DBP物種。另外，根據C-DBPs流佈調查結果，可利用建立的模式以飲用水中THMs生成濃度來預測HAAs的生成（HAA9 = 1.824 × TTHM0.735，R2=0.678，P<0.005）。
第二階段中DON擬似物質與DBPs生成特性的試驗結果顯示，除了已知亞硝胺類化合物之重要前驅物-Dimethylamine (DMA)之外，benzalkonium chloride (BKC)和3-(N,N-dimethyloctyl-ammonio)propanesulfonate (3-N,N-DAPSIS)也是生成C-DBPs（TTHM生成可達2700 μg/L）及N-DBPs（NDMA生成可高達2×105 ng/L）之重要前驅物質。接著選取DMA、BKC及3-N,N-DAPSIS進行進一步的試驗，結果顯示DBPs生成隨著反應溫度增加而顯著地增加；但由於各物質之結構、物化特性及與消毒劑反應機制之不同，故DBPs生成趨勢與pH間之關連性並不一致。另外，水中溴離子的添加，也顯著提高含溴DBPs之生成比例。
第三階段實場水樣中DON組成的分析結果顯示，除了amphiphilic bases/neutrals (AMPB/N)成分外，放流水及原水樣本中各DON組成比例相似，且具有下列分佈趨勢：hydrophobic acids (HPOA) > hydrophilic acids/neutrals (HPIA/N) > hydrophilic bases (HPIB) > amphiphilic acids (AMPA) > hydrophobic bases/neutrals (HPOB/N) > amino acids (AA)。最後，將各季節取得之同樣DON組成分離物質混合，進行DBPs生成反應，AA可生成最多量的C-DBPs（THMs生成濃度可達1258.2 μg/L），而AMPB/N則可生成最多量之NDMA（生成濃度可高達9238.0 ng/L）。

關鍵字

三鹵甲烷 ； 生成潛能 ； 含鹵乙酸 ； 亞硝胺 ； 消毒副產物 ； 流佈 ； 溶解性有機氮

並列摘要

Disinfectants used in water treatments can react with the organic materials to form various disinfection by-products (DBPs). The carbonated DBPs (C-DBPs), which mainly include trihalomethanes (THMs) and haloacetic acids (HAAs) in drinking water, have been shown to possess different kinds of toxicities, mutagenicities and carcinogenicities. Due to the analytical limitation and lack of regulation for HAAs in drinking water, the database for distribution of HAAs in drinking water has been not available in Taiwan. Nitrosamines are a class of emerging nitrogenated DBPs (N-DBPs), which are mainly formed with treatments of chloramination, and far more carcinogenic than traditional C-DBPs. Among nitrosamines, N-nitrosodimethylamine (NDMA) is the dominant species in drinking water. Besides chloramines, dissolved organic nitrogen (DON) compounds have been recognized as important precursors of nitrosamines and many of them have not been identified.
This study included three objectives: (1) to establish the preliminary database of HAAs and THMs in Taiwan based on water samples collected from 141 water treatment plants (WTPs) between 2007 and 2009. (2) Nine representative nitrogenous organic compounds with different DON characteristics and structures were selected to react with free chlorine, chlorine dioxide and monochloramine for their DBP formation characteristics (nitrosamines, THMs and HAAs). (3) A modified DON fractionation method (DAX-8, XAD-4 and MSC-1H resins) was used to fractionate the seasonal effluents of Neihu wastewater treatment plant in Taipei City (TN) and source waters of Tai Lake WTP in Kinmen (KT).
The concentrations of HAAs were distributed from 0.5 to 84.4 μg/L and those of THMs were from ND to 133.2 μg/L. Due to the various raw water qualities, the C-DBP concentrations showed the seasonal and geographical variations in different parts of Taiwan, and a higher portions of brominated species was observed in the off-shore island WTPs. Moreover, statistically significant (P<0.005) logarithmic linear regression models were also proposed to describe the correlations between the total THMs (TTHM) and HAAs (HAA5=1.219×TTHM0.754; HAA9=1.824×TTHM0.735).
In the DBPs formation tests of surrogate compounds, dimethylamine (DMA), benzyldimethyltetradecylamine (benzalkonium chloride, BKC) and 3-(N,N-dimethyloctyl-ammonio)propanesulfonate (3-N,N-DAPSIS) inner salt were identified as potent precursors for C-DBPs (up to 2700 μg/L of THMs) and N-DBPs (up to 2×105 ng/L of NDMA). Then, further studies of DMA, 3-N,N-DAPSIS and BKC were performed to determine the impact of pH, reaction temperature and bromide concentration on DBP formations. The DBP yields apparently increased with rising temperature, however, no consistent correlations were observed between DBPs yields and pH. Bromide shifted the DBP species into brominated DBPs, and this phenomenon was more apparent when BKC was treated with chloramine.
For the survey of DON distributions and compositions, both TN and KT samples had similar compositions of DON fractions except for AMPB/N isolate to show the general trend: HPOA > HPIA/N > HPIB > AMPA > HPOB/N > AA. Finally, seasonal isolate samples were mixed to perform the DBPFPs with the three disinfectants mentioned previously. It was found that the AA fraction formed the highest amounts of C-DBPs (up to 1258.2 μg/L of THMs), and the AMPB/N fraction could form as high as 9238.0 ng/L of NDMA at 10 mg/L of NPDOC.

並列關鍵字

Disinfection by-products ； Dissolved organic nitrogenous ； Distribution ； Formation potential ； Haloacetic acids ； Nitrosamines ； Trihalomethanes

參考文獻

Aiken, G. and Cotsaris, E. (1995). Soil and hydrology-their effect on NOM. Journal American Water Works Association. 87, 36-45.

Alberts, J.J. and Takacs, M. (1999). Importance of humic substances for carbon and nitrogen transport into southeastern United States estuaries. Organic Geochemistry. 30, 385-395.

American Public Health Association (APHA) (1998). Standard methods for the examination of water and wastewater, 20th edition. American Water Works Association & Water Environment Federation, APHA-AWWA-WEF. Washington, D.C., USA.

Austin, E.W., Parrish, J.M., Kinder, D.H. and Bull R.J. (1996). Lipid peroxidation and formation of 8-hydroxydeoxyguanosine from acute doses of halogenated acetic acids. Fundamental and Applied Toxicology. 31 (1), 77-82.

Badr, E.S.A., Tappin, A.D. and Achterberg, E.P. (2008). Distributions and seasonal variability of dissolved organic nitrogen in two estuaries in SW England. Marine Chemistry. 110 (3-4), 153-164.